All drinking water that runs from the tap on Schiermonnikoog is extracted from the island. Much of the rain that falls, immediately flows away via the ditches and the beach into the sea or vaporizes. But part of this rainwater penetrates the sandy ground and becomes part of the natural freshwater bubble below the island, which on some places comes to the surface and forms dune lakes.
Because tourism has grown substantially during the last decades, the use of drinking water also has increased. This may cause wet dune valleys, where many rare plants and animals live, to dry up. Natuurmonumenten, Wetterskip Fryslân and water company Vitens intend to prevent this. During the last years water extraction partially has been moved to the Westerplas, to relieve vulnerable dune areas. The coming years the Wetterskip will implement a local water plan. One of its goals will be to keep more rainwater on the island, to prevent the dunes from running dry.